vim_clean.py

"""
Clean up unnecessary whitespace in a file.
Also fix tabs-to-spaces.
"""

# Must be called from within vim; can't run stand-alone.
import vim

def remove_trailing_spaces(buff):
    """
    Clean up accidental whitespace at the end of lines.
    """
    for (index, _) in enumerate(buff):
        buff[index] = buff[index].rstrip()

def remove_blank_lines(buff):
    """
    Remove blank lines if there is more than one in a row.
    Allows two lines before a class declaration.
    """
    cleaned = False
    for (index, line) in enumerate(buff):
        # If the line isn't blank, skip it; the remainder of
        # this function only deletes duplicate blank lines.
        if line.strip():
            continue

        # If it's an extra blank line but before a
        # class definition, then leave it alone.
        try:
            third_line = buff[index + 2]
            if third_line.strip().startswith('class'):
                continue
        except IndexError:
            pass

        # Get the next line. If there is no next line, treat
        # it like a blank line.
        try:
            next_line = buff[index + 1].strip()
        except IndexError:
            next_line = ''

        # If this is a duplicate blank line, or a blank line at
        # the end of a file, then get rid of it.
        if not next_line.strip():
            del buff[index]
            cleaned = True

    # Because we re-size the buffer each time we make a change, start
    # over with a fresh copy of the buffer after each destructive change.
    if cleaned:
        remove_blank_lines(buff)

def replace_tabs(buff):
    """
    Replace tab characters with four spaces.
    """
    text = '\n'.join(buff)
    text = text.replace('\t', '    ')
    buff[:] = text.split('\n')

def main():
    """
    Clean up whitespace!
    """
    remove_blank_lines(vim.current.buffer)
    remove_trailing_spaces(vim.current.buffer)
    replace_tabs(vim.current.buffer)

main()